Identification and Quantitation of Reaction Products from Quinic Acid, Quinic Acid Lactone, and Chlorogenic Acid with Strecker Aldehydes in Roasted Coffee

J Agric Food Chem. 2021 Jan 27;69(3):1027-1038. doi: 10.1021/acs.jafc.0c06887. Epub 2021 Jan 12.

Abstract

To gain comprehensive insight into the interactions of key coffee odorants, like the Strecker aldehydes, acetaldehyde, propanal, methylpropanal, 2- and 3-methylbutanal, and methional, and the nonvolatile fraction of coffee, an untargeted metabolomics approach was applied. Ultra performance liquid chromatography (UPLC)-time of flight (TOF)-mass spectrometry (ESI-) profiling followed by statistical data analysis revealed a marker substance for a coffee beverage spiked with acetaldehyde with an accurate mass of 217.0703 [M - H]-. This compound could be identified as a reaction product of quinic acid (QA) and acetaldehyde linked by acetalization at the cis-diol function of QA. Consequently, the acetalization of aldehydes, QA, 5-O-caffeoyl quinic acid (CQA), and quinic acid γ-lactone (QAL) was investigated by means of model reactions, followed by synthesis, isolation, and structure elucidation via UPLC-TOF-MS and 1D and 2D NMR techniques. UHPLC-MS/MSMRM screening and the quantification of aldehyde adducts in coffee beverages revealed the presence of QA/acetaldehyde, -/propanal, -/methylpropanal, and -/methional reaction products and CQA/acetaldehyde, -/propanal, -/methylpropanal, -/2- and 3-methylbutanal, and -/methional and QAL/acetaldehyde adducts for the first time, in concentrations of 12-270 μg/L for QA/aldehydes, 5-225 μg/L for CQA/aldehydes, and 62-173 μg/L for QAL/acetaldehyde. The sensory characterization of the identified compounds showed bitter taste recognition thresholds of 48-297 μmol/L for CQA adducts and 658 μmol/L for QAL/acetaldehyde, while the QA adducts showed no bitter taste (<2000 μmol/L).

Keywords: Strecker aldehydes; aroma staling; chlorogenic acid; low molecular weight fraction; quinic acid; quinic acid lactone; roasted coffee; untargeted UPLC−TOF-MS screening.

MeSH terms

  • Adult
  • Aldehydes / chemistry*
  • Chlorogenic Acid / chemistry*
  • Chromatography, High Pressure Liquid
  • Coffea / chemistry*
  • Coffee / chemistry
  • Cooking
  • Female
  • Hot Temperature
  • Humans
  • Lactones / chemistry*
  • Male
  • Molecular Structure
  • Quinic Acid / chemistry*
  • Seeds / chemistry
  • Tandem Mass Spectrometry
  • Taste
  • Young Adult

Substances

  • Aldehydes
  • Coffee
  • Lactones
  • Quinic Acid
  • Chlorogenic Acid